In the event of withdrawal of participation, affected subjects will be suppressed from analysis (i.e. analysis will be performed on a per protocol basis), or in the event that isolated iliac DVT is diagnosed following vascular technologist suspicion. Isolated iliac DVT diagnosed after additional imaging resulting from technologist suspicion will be analyzed as an additional outcome variable, and the rate of this diagnosis reported with a corresponding exact 95% confidence interval. Use of intention-to-treat analysis could bias results of the study in the case of withdrawn subjects as they would, by definition, not complete the defined follow-up period and would not have ascertainment of the primary study outcome.